1. Field of the Invention
The present invention relates to a process and a device for detecting the current phase of operation of a system with multiple phases of operation. A "system with multiple phases of operation" is understood to mean, in the context of the present invention, any complex system such as for example a railway, a nuclear power station, a helicopter, an airplane, etc., the operation of which is controlled by one or more operators and is ordinarily broken down into characteristic steps such as, for example, checks before powering-up, checks after powering-up, start-up, low-speed operation before throttling-up the power, the first phase of throttling-up the power, etc., the switching from one step to the next being conditioned by the obtaining of certain performance indices or the achieving of certain objectives (stabilization of an electrical voltage, crossing of a speed threshold, etc.).
Although the present invention is thus applicable to numerous systems, it will be described below more particularly in the context of an airplane, more particularly a transport airplane, the operation of which is controlled by a crew.
2. Broad Description of the Invention
It is known that the "operation" of a transport airplane can be broken down into various phases, such as for example stopped on the ground, take-off, climb, cruising flight, descent, landing, etc.
With each of these phases there are associated operating domains sanctioned by the constructor or recommended as a function of the conditions of utilization and, consequently, the boundaries of these domains, the diverse technical and operational instructions, operations or controls, etc.
The technical and operational documentation (flight manual, operations manual, etc.) for a specified airplane takes account of this. The same is true for the procedures or associated checks, taking the form in particular of "check lists".
The flight crew is, of course, aware of the flight phase which the airplane is in. However, experience has shown abundantly that the crew is liable to make errors of various kinds. When wishing, therefore, either to assist the crew by presenting appropriate information, or to carry out a certain number of controls or checks affecting safety, operational efficiency, etc., during the flight, it is very useful, or even indispensable, to identify the present flight phase.
It is not desirable to ask the crew to provide this information; this would be an unacceptable overburden and another source of error. This identification must therefore be, on the one hand, automatic and, on the other hand, efficient in the presence of the majority of plausible crew errors.
The object of the present invention is therefore to detect, independently of the operators controlling the operation of a system, the current phase of operation of the said system. More particularly, in the application of the invention to an airplane, this object is the production of an airborne device, that is to say one capable of being installed on board and of operating there, with response times which are compatible with the usage made thereof, which is able to detect the present operational phase automatically, and to do so even in the presence of the greatest possible number of crew errors regarded as practically possible.
It will be noted that phase detection algorithms currently used on board airplanes are already known. However, these known algorithms use criteria which mix together indiscriminately measurements corresponding to the state parameters of the airplane (altitude, speed, engine thrust, etc.) and reports of actions by the crew presumed to correspond to a flight phase (lowering of the landing gear, lowering of the slats and flaps, choice of the mode of operation of the automatic pilot, etc.).
Thus, these known algorithms involve, in the detection of the flight phase, direct actions by crews susceptible to errors of handling or incorrect representation of the actual situation of the airplane. Moreover, the currently existing algorithms are matched to the specific need of the function of the computer in which they are installed.
The object of the present invention is therefore to alleviate the disadvantages of these known algorithms by delivering an independent item of information regarding the crew's conception of the actual situation of the airplane, including the flight phase.
To this end, according to the invention, the process for detecting the current phase of operation of a system with multiple phases of operation, is notable in that:
the said operation is partitioned into a set of phases, so that each phase corresponds to a partial domain of the operation of the said system, and so that the said set of phases covers the whole of the said operation; PA1 a reference phase is chosen from the said phases of the said set; PA1 for each of the said phases, the set of possible switches to the other phases is determined; PA1 for each of the said switches, a set of parameters characteristic of the said switch is defined; PA1 the said sets of parameters are detected continuously; PA1 with the aid of the variations in the said parameters, the chain of switches actually involved is determined on the basis of the said reference phase; and PA1 the said current phase of operation is deduced from the said chain of switches.
Thus, contrary to the known prior technique described above with its disadvantages, according to the invention the current phase of operation is determined not through the state of a certain number of parameters specific to the said phase, but through the variation in parameters on transferring (or switching) from one phase to another.
By virtue of the invention, the current phase of operation is therefore determined with the aid of a reference phase and switches of phases involved between the said reference phase and the said current phase.
In the case of an airplane, the said reference phase is preferably chosen as being the stopped on the ground phase. Indeed, on the ground, when powering-up or when starting the first engine, the airplane is in a phase of operation which is known with certainty. It may either remain thus, or depart therefrom, and the only other phase which it may enter is that of travelling over the ground, subject to a switch of phase. The latter, in its turn, can give way to nothing other than a return to stopped on the ground or to the take-off run. Hence, gradually, from among the physically possible switches, the one which has--or has not--taken place is determined.
Moreover, it is known that very many parameters are measured permanently on airplanes; some are presented to the crew, others are not but constitute information necessary for the correct operation of the various systems of the airplane. The monitoring of some of these parameters and the execution of associated logic tests make it possible (trial flights and very special technical flights excluded) to determine that a switch of phase has taken place.
In order to guard against possible errors by the crew, several logic tests are preferably undertaken which appeal to different parameters or sequences of parameters and are carried out in parallel. A switch is preferably detected only if one at least of the logic itineraries declares it (unless, for the sake of redundancy, several out of the possible itineraries are desired to detect the switch). By way of example, the "lower landing gear" parameter may be involved in such a logic sequence. However, in order to guard against omitting to lower this gear, it will be necessary for some other logic sequence not involving the position of the gear to be able to lead to the desired check.
The more or less fine partitioning of the operation into phases depends on the uses to which the identifications of phases are to be put for a specified airplane. The partitioning presented below by way of example is therefore not the only possible one.
Likewise, the detailed definition of the tests depends on the airplane by reason of its configuration (type of engines, existence or absence of movable slats, etc.) and its relevant parameters. The critical values of the numerical or logic variables also depend on the type of airplane.
In the case of a transport airplane, operation is generally partitioned into about ten phases. By way of example, a partitioning into ten phases may be considered, corresponding respectively to stopped on the ground, slow travelling over the ground, fast travelling over the ground (take-off), initial climb, climb, cruising flight or holding level, descent, initial approach, final approach and overshoot.
Among the characteristic switch parameters may be used, in particular, the switching of the engines from stopped to running and vice versa, the changing of engine speed, the crossing of speed thresholds in relation to the travelling over the ground speed, the switching of the landing gear from the compressed state to the relieved state and vice versa, the changing of sign of the vertical speed, the crossing of thresholds in relation to the vertical speed, the crossing of thresholds in relation to the altitude, the changing of sign of the variation in altitude and the crossing of thresholds in relation to the variation in altitude. These various thresholds may be mathematical functions of certain operating or flight parameters.
Furthermore, certain of the relevant parameters, as for example speed or altitude, exhibit a relatively straightforward long-term movement, but a more or less erratic momentary movement. Consequently, control of the crossing of predefined thresholds by these parameters often requires that they be previously smoothed by way of appropriate time constants.
It will be noted that the state of the engines, the speed of the engines, the travelling over the ground speed, the vertical speed, the altitude, the variation in altitude, etc., constitute information available on board an airplane and delivered by sensors or computers which generally exist on board. The compressed or relieved state of the landing gear can be detected by a sensor consisting of a simple interrupter. The same is true for other information, such as the deployment or retraction of aerodynamic surfaces, such as high-lift slats and flaps, as well as the .deployment or retraction of a thrust reverser. Thus, the switching of these aerodynamic surfaces and the thrust reverser from deployment to retraction and vice versa can also be used as phase switch parameter.
For the implementation of the process according to the present invention, there are therefore advantageously provided a device including a set of sensors delivering information whose change of state or of value is representative of the said switches between phases and a computer receiving the information from the said set of sensors, knowing the reference phase, and containing in memory thresholds, and possibly laws for the movements of these thresholds, for at least some of the said information. This computer therefore carries out the various logic tests mentioned above.
The information received by the computer can originate either from sensors specially installed for the implementation of the process according to the invention, or from sensors or processors existing on board the airplane.
Thus, the said computer, which may be analog or digital or which knows the reference phase, may carry out the appropriate tests in order to detect the said switches of phase. It therefore provides its output with the signals representative of the current phase of operation, the said signals being usable for display purposes or being transmittable to other devices or computers able to utilize them.
It is thus seen that, by virtue of the invention and in the case where the system is an airplane, an onboard device is produced, capable of detecting the present operational flight phase, automatically and even in the presence of the greatest number of crew errors regarded as practically possible.
The figures of the attached drawing will clearly elucidate the manner in which the invention may be embodied. In these figures, identical references denote similar elements.